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Carcinoscorpius rotundicauda (Mangrove Horseshoe Crab)

Large crab-like animal with a roughly horseshoe-shaped shell and a long, straight tail spine. The underside is equipped with numerous legs.

Very similar to the more familiar North American horseshoe crab Limulus, but immediately distinguishable by the shape of its tail spine. In cross section this species has a circular tail spine, whereas a cross section of the tail spine of Limulus is polygonal.

Occasionally traded as a freshwater species, this animals needs at least moderately saline brackish water conditions to survive, and is arguably best kept as a high-end brackish to marine animal.

Fish information (behaviour and breeding):

Horseshoe crabs generally can be difficult to maintain in captivity, and this species is no exception. It requires a sandy substrate through which it can dig, preferably sufficiently deep that the animal can completely cover itself. Coral sand or smooth-grade silica sand can be used.

The mangrove horseshoe crab is rather large, with a shell length of 20-40 cm when mature, and a tail spine that is at least as long as the body. Being rather inflexible animals they should only be kept in tanks that offer sufficient space for them to turn around easily. In other words, the width and length of the tank will need to be at least 2-3 times the total length of the horseshoe crab including its tail spine. Depth is not critical.

Horseshoe crabs are opportunistic feeders, grubbing about in the substrate for small invertebrates and carrion. In captivity they will eat most small live or frozen foods including bloodworms, chopped seafood, etc, but making sure that the crab gets enough to eat can be tricky. Take care not to combine with other bottom feeders except perhaps snails. These animals are not predatory and could be mixed easily with midwater brackish water fish such as mollies, archers or monos.

Family Group: Snails and Crustaceans
Distribution South and Southeast Asia
Temperature 24-26 C
Size Up to 40 cm excluding the tail spine
Water Parameters Brackish, SG 1.010+
Water PH 7.5-8.5
Care Level Expert only
Water Chemistry More than pH 7 - Alkaline
Schooling Fish No
Sociability Peaceful
Diet Special Needs

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